Art of making cement-fiber board.



JAMES E. LAPPEN, 0F WINONA, MINNESOTA.

ART OF MAKING CEMENT-FIBER BOARD.

No Drawing.

To all whom it may concern.-

Be it known that I, JAMES E. LAPPEN, a citizen of the United States, residing'at Winona, in the county of Winona and State mechanical blows, and are waterproof and fireproof, while they also have other characteristics common to wooden boards, such as a certain fibrous tenacity which prevents them from being easily chipped and cracked, and which makes it possible to trim or shape them by means of a saw, and to secure them to a supporting structure by simply driving nails through them. Owing to the nonbrittle character of the board due to its fibrous constituents such nailing can be done without cracking or chipping the board. Like wooden boards also, these cement fiber boards have a certain amount of resiliencewhich makes it possible to bend them within certain limits. All of thesecharacteristics make them especially desirable for use in place of ordinary wooden shingles.

Boards or plates of this general character have heretofore been made by mixing the fibrous material, such as asbestos, with hydraulic cement in the presence of a great bulk of water, and then by building this material up layer by layer into laminated plates of the desired thickness in the manner of making cardboard upon an ordinary cardboard machine, or so called wet machine. In this way the finished product does not have a homogeneous character but is in layers which can be easily detected by examining the physical structure of the product, and even the layers themselves are not homogeneous because the cement, being heavier, settles at the bottom of each layer.

Furthermore, by the use of this process the cement, being heavier, naturally settles in the watery mixture, so that it comes next to the traveling apron, and will fill up the fibrous surface or pores thereof, thus clogging the apron so that the water which is squeezed out from the mixture cannot get Specification of Letters Patent.

Application filed August 5, 1916. Serial 110,113,236.

through the apron but will run off the sides thereof and carry with it part of the material.

It is the object of the present invention, among other things, to construct these fibercement boards in such manner that the cement does not initially come in contact with the apron at all, thereby avoiding the clogging of the apron and the consequent necessity of frequently cleaning the same to remove the accumulation of cement, as well as to make the board in such way that the cement and fiber shall be intimately mixed through the thickness of the board so that the product, instead of being in non-homogeneous layers, will be homogeneous throughout its thickness with the cement evenly distributed among and about the fibers, without using any greater pressure than such as is naturally incident to the building up of the board in the manner of the usual card-board process.

With these objects in view my process consists, generally speaking, in first disintegrating the fibrous ingredients, such as asbestos and mineral wool, in water until the fibers are well separated and'dispersed through the water, and then, after partially drainingthe fibers-and collecting them into a thin film, carrying the wet fibrous film under and past a source of dry cement powder and sprinkling the powdered cement evenly over the surface of the film as it is carried along, and lastly building up the thin layers or films of wet fibrous material thus sprinkled with dry cement into boards or plates of the required thickness, and exerting upon them as they are being built up sufiicient pressure to force the cement into and through the wet fibrous mass, thereby impregnating the entire mass with cement and making it homogeneous in character.

In carrying out the process I first disintegrate the desired quantity of fibrous material in water so as to separate the fibers and put them into the vat of the well-known volving cylinder used in wet machines of this character, through the application of suction to the interior'of the cylinder in a manner well known in the art. At the top of its revolution the screened cylinder comes in contact with a felt belting which is pressed into contact with the gauze surface of the cylinder by means of a couch roll, whereby the Wet fibrous film adheres to the belt which peels it ofi from the gauze cylinder and carries it to and between a pair of .rolls, the upper of which is commonly known as the accumulator roll.

During the passage of the fibrous material from the couch roll to the accumulator roll dry powdered cement is sprinkled and evenly distributed over the film or stratum of wetted fiber, so as to cover the surface of the wetted material with dry powdered cement. When the cementcovered fibrous material reaches the accumulator roll it is peeled off from the belt by its greater adhesion to the accumulator. roll, against which it is pressed by means of the co-acting roll on the under side of the accumulator roll. In the continued revolution of the accumulator roll one layer of this cement-powdered fibrous material after another is peeled ofi' the belt and wrapped about the accumulator roll until the accumulated layers reach the desired thickness, whereupon the sheet so formed is cut from the roll in a manner well known in the art. As the layers pass between the press rolls, meaning thereby the accumulator roll and its coacting pressure roll, this dry cement is driven through the' wet mass of-fiber so as to come into intimate association with the fibers throughout the entire thickness of the accumulated sheet, so that the sheet will become a uniform homogeneous mass without any layers that can be detected by examining the physical structure of the sheet. It will therefore be seen that by the use 0 this process I avoid the difficulty which is inherent in a process where the cement and fibrous material are mixed together in water before being fed to the apron or belt, of having the cement collect upon the surface of the belt'and fill up the fibers or pores thereof so that the water squeezed out from the mass cannot pass through the apron but washes the material out at the side; and the cement-fiber boards produced by the present Erocess are much stronger than boards made y mixing the cement and fibers in water before passing the material through the cardboard machine, because the fibers are more uniformly and thoroughly intermingled with the cement when the cementis'added subsequently in dry form than they would beif the cement and fibers were mixed initially with water, for. this allows the cement to settle and separate "out from the fibers.

The proportions of the ingredients used can be varied within certain limits but I have secured the best results by using 400 pounds of fibrous material to 600 pounds of der pressure until a sheet of the desiredv thickness is formed.

2. The herein described process of producing cement-fiber board which consists in first disintegrating mineral fibrous material in water, then separating the disintegrated fibers out from the water and collecting them into a thin wet film, then carrying the film continuously under a source of dry cement powder and sprinkling the surface of the traveling film with said powder and "then wrapping the film upon itself layer upon layer and at the same time subjecting it to pressure until a sheet of the desired thick ness is formed.

3. The herein described process of producing cement-fiber board which consists in disintegrating a major amount of mineral wool then separating the disintegrated fibers out from the water and collecting themi into a thin wet film, then sprinkling the surface of the film with dry cement powder, and then wrapping the film upon itself under pressure until a sheet of the desired thickness is formed.

4; A product of the herein described Proc-' ess, made by first disintegrating mineral fibrous material in water, then causing the wet disintegrated fibers to be spread out in a thin film, then sprinkling the film with dry cement powder, and finally wrapping the film upon itself, layer upon layer, under pressure substanti'ally as described.

In testimony whereof I afiix in presence of two Witnesses.

JAMES E. LAJEPEN.-

Witnesses:

ARTHUR P. LoTHRor, BEATRICE BROWN,

and a minor amount of asbestos in water my signature 

